Sharks and Relatives

What are Sharks and Relatives? Sharks and their relatives, the skates, rays, and chimaeras (batfish), are all cartilaginous fishes and belong to the group Chondrichthyes. Their skeletons are composed of cartilage, which is often hardened with the addition of calcium phosphate but is not true bone. Most extinct members of this group looked generally like their modern relatives. Chondrichthyans first appear in the fossil record in the Devonian, and since then, they have taken on many different forms and moved into many marine and freshwater habitats.

First known fossil occurrence: Devonian.

Last known fossil occurrence: Quaternary. This group has living relatives.